Allow sharing of actions and decisions

[ftsell]

Is your feature request related to a problem? Please describe.

Nope not really, I just think it would be neat.

In general I would like to see the ability to share some actions and decisions between different DSDs. For example we could have a decision on whether our robot is currently in a FALLEN state and reuse that information in localization and hcm.

Describe the solution you'd like

Similar on how python allows modules to live in different directories I would like to see DSD elements to live in different modules.
Keeping in the similarity we could simply search through different modules by having a PYTHONPATH-like environment variable which lists modules in which modules can be located.
It would not need to be an environment variable but could also be a parameter just like you currently need to give register_actions and register_decisions a string path.